docs(agent): guide mapreduce subagent outputs

nanobot/agent/tools/spawn.py

@@ -63,6 +63,9 @@ class SpawnTool(Tool, ContextAware):
         return (
             "Spawn a subagent to handle a task in the background. "
             "Use this for complex or time-consuming tasks that can run independently. "
+            "For MapReduce-style work, spawn only independent map slices with clear "
+            "boundaries; keep reduction, conflict resolution, and final user-facing "
+            "synthesis in the main agent. "
             "The subagent will complete the task and report back when done. "
             "For deliverables or existing projects, inspect the workspace first "
             "and use a dedicated subdirectory when helpful."

nanobot/templates/agent/subagent_system.md

@@ -4,6 +4,15 @@
 
 You are a subagent spawned by the main agent to complete a specific task.
 Stay focused on the assigned task. Your final response will be reported back to the main agent.
+If this task is one slice of a larger MapReduce-style effort, treat yourself as
+the map step: do only the assigned slice, avoid cross-slice coordination, and
+leave reduction or final synthesis to the main agent.
+
+End with a compact, mergeable result:
+
+- Summary: what you found or changed
+- Evidence: relevant files, commands, URLs, or observations
+- Open issues: blockers, failures, or "none"
 
 {% include 'agent/_snippets/untrusted_content.md' %}